ZIL+L2ARC

[prescott]

Is it possible to put two SSDs into a mirror where half of space is used for ZIL and half for L2ARC?

 

[cyberjock]

This has been discussed many times in the forums.

Yes, it's technically possible if you are okay with some hackjob. The problem is the ZIL will be constantly using the SSD and the L2ARC will not write to a disk that unless it's been idle for a certain timeframe. Or in other words, it will make both your ZIL and L2ARC useless. So don't try to do this as it's just a waste of your money buying the SSDs for no benefit.

 

[prescott]

Ok I understand. If I have max 2 ports available for use with FreeNAS which I'm not gonna fill anymore with spindles, is it smart to use 1 SSD for ZIL and 1 SSD for L2ARC? Shouldn't ZIL be mirrored? In other words what would YOU do?

Thanks!

 

[no_connection]

I would use SSD for things that need centralized storage with high IO.

Spinning rust should more than enough keep up with normal streaming IO for the rest.

What workload would actually benefit from L2ARC in the first place?
Or ZIL for that matter.

 

[prescott]

Well, I have 6x 4TB Blacks in raidz2 for storage for 5-10 users that are not very heavy; and on it is a NFS share for ESXi datastore which is painfully low, which I thought ZIL/L2ARC would speed things up?

Thanks!

 

[prescott]

Is Intel S3500 80GB SSD good for ZIL with 100MB/s writes or is it a bottleneck for a pool like this?